Apparatus for removing coatings



June 1959 w. ACKERMANN APPARATUS FOR REMOVING commas Filed Aug. so. 1956INVENTOR.

WA LTER AEKER'MANN United. States Patent 2,891,433- APPARATUS FORREMOVING GGA'IIIIGS Lyndhurst, N.J., assignor to Radio Walter Ackermann,

a corporation of Delaware 1 This? invention relates tov improved methodandr apparams for removingfriable, coatings from support members and,particularly although not exclusively, for removing friable insulatingcoatingsfrom wires employed as heaterelements in electron dischargetubes; whereby the electrical connection of these wires to otherelements is facilitated.

One type of apparatus for removing friable insulating coatings fromelectrical wires utilizes a pair of hammers which are brought intocontact with diametrically opposed portions of the coated wire placedbetween them. The impact of the hammers crushes the insulation whichfalls away from the wire to leave a bare portion. Although suchapparatus does a comparatively eificient job, particles of theinsulation may remain on the wire and may prevent the formation of goodsoldered or welded joints.

The objects of the present invention concern the provision of improvedmethod and apparatus for removing friable insulating coatings from wiresor other support members.

In general, the method of the invention comprises applying a crushingforce to a portion of the insulation of a wire and then, with thecrushing force still applied, rotating the wire to expose all of theperiphery of the coating to the crushing force.

Apparatus embodying the principles of the invention comprises a pair ofhammers having opposed crushing surfaces. Means are provided forbringing the hammers together in axial alignment so that they crush -aportion of the insulating coating of a wire which is positioned betweenthem. Means are also provided for vibrating at least one of the hammerswhile the hammers are in contact with the wire so that other portions ofthe insulating coating are crushed and may be readily removed.

The invention is described in greater detail by reference to the drawingwherein:

Fig. 1 is a plan view of apparaus embodying the principles of theinvention; and,

Fig. 2 is an elevational view of the apparatus of Fig. 1.

The apparatus and method of the invention are particularly useful inremoving selected portions of the insulating coating of an electron tubeheater wire to provide bare portions of wire which may be welded orsoldered to suitable leads within an electron tube. Such a wire iscylindrical in form and comprises a metal core 12 having an insulatingcoating 14, of for example, aluminum oxide.

Apparatus 16 for removing portions of the insulating coating from thewire 10 includes a pair of hammers 18 and 20 made of tungsten carbide orother material suitable for the intended purpose. The hammers 18 and 20have planar crushing surfaces 22 and 24, respectively, and the hammersare adapted to be axially aligned with the crushing surfaces paralleland face to face when the apparatus is in operation.

The hammer 18 is secured between a pair of plates 2,891,433 PatentedJune-23,1 1 959- 262and: 28iwitli' a lip 29 formed ontthehammerirestingt oma. shoulder 30 formed in the plate 28;. The: plates 26and 28 are held together by bolts 31rtorform a ham men assembly-which:itself is secured to a: support arm 321bya bolt34 secured at its freeend-to 'asuitable'suw poi-t member 36'; The'free end of thesupportarm isalso :provided with: gear" teeth: 38 which mesh with a gearrackz40iand1the: gear rack .40 is connected'to a piston rod 42 ofiaconventional'double-acting air cylinder 44. The air cylinder has. airinlet pipes 46 and 48" which are con nected to a source. of air"(notshown);

Thehammer 20 is secured between a pair of-plates? 50 andSZ-with alip-S3' form'ed'on the hammen resting on: a shoulder 54 formed on theplate 52: The' plates 50 and 52: are helds together: by bolts: 55tofbrm: a hammer as sembly; which itself is=secured to a support arm561' by a: bolt 58:- Tliepressure betweenthe platesi50: and 52 issuflicient to: hold the: hammer securely: while: allow ing it tomoverlaterally; between: therplatesaasz-showrt by the arrows 59 inFig. 1. The support arm 56 is secured to the support member 36 at itsfree end which is provided with gear teeth 60 which mesh with the gearrack 40.

According to the invention, means are provided for vibrating oroscillating one or both of the hammers 18 and 20. One such arrangementis shown for vibrating the hammer 20 and includes a lateral projectingportion 62 from the hammer, the projecting portion being secured to oneend of an armature 64 the other end of which is suitably secured to thehousing of a relay coil 66. The armature 64 is spaced from the plates 50and 52 and its path of vibration is limited by stops 68 and 70 on thecoil 66 and plate 50, respectively. The coil 66 is secured to thesupport arm 36 by a bracket 72 and it is electrically connected througha switch 74 to a source 76 of alternating voltage.

In operation of the apparatus 16, the wire 10 is positioned between thehammers 18 and 20 which are open and spaced apart. In this position ofthe hammers, air is flowing through, for example, the inlet pipe 46 intothe air cylinder 44 and the piston rod 42 is held in its most forwardposition so that the support arms and hammers are remote from eachother. The air flow to the air cylinder is then switched into the inletpipe 48 and the piston rod is driven to its most rearward position. Asthe piston rod moves, the support arms 32 and 56 rotate toward eachother and the hammers come together in axial alignment and the crushingsurfaces 22 and 24 thereof contact diametrically opposed portions of thecoating 14 on the wire 10 with sufiicient force to crush these portionsof the coating. With the hammers thus held against the wire, the switch74 is closed and the relay coil 66 is energized and the armature 64 isvibrated. At the same time, the hammer 20 vibrates or oscillates in apath transverse to the longitudinal axis of the wire 10 and its crushingsurface 22 moves back and forth substantially parallel to the crushingsurface 24 of the hammer 18 which is held stationary. This relativemovement between the crushing surfaces of the hammers causes the wire 10to rotate between the hammers as shown by the arrow and a completeannular portion of the coating is crushed and falls away from the core12 to provide a bare leg 78 (Fig. 2).

Air flow to the air cylinder 44 is then switched into the inlet pipe 46,the piston rod 40 is driven forward and the support arms 32 and 56 andthe hammers 18 and 20 are driven apart. The wire 10 is then removed andready to have an electrical connection made to the bare portion formedby the crushing operation.

What is claimed is:

1. Apparatus for removing a friable coating from a structure consistingof a core having said coating thereon comprising a pair of relativelymovable hammers, means for bringing said hammers into contact with saidcoating whereby said hammers crush a portion of said coating when saidstructure is positioned between said hammers, and means for vibratingone of said hammers whereby other portions of said coating are crushedbetween said hammers.

2. Apparatus for removing a friable coating from a structure consistingof a core having said coating thereon comprising a pair of relativelymovable hammers, means for bringing said hammers into axial alignmentand into contact with said structure when said structure is positionedbetween said hammers, and means for os cillating one of said hammers ina path transverse to the longitudinal axis of said structure.

3. Apparatus for removing a friable coating from a structure consistingof a core having said coating thereon, comprising a pair of relativelymovable hammers having planar crushing surfaces, means for bringing saidhammers into axial alignment with said crushing sur- 20 faces face toface and parallel to each other, and means for oscillating one of saidhammers in a path parallel to the crushing surface of the other hammer.

4. Apparatus for removing a friable coating from a cylindrical structureconsisting of a core having said coating thereon comprising a pair ofrelatively movable hammers, means for bringing said hammers into axialalignment and into contact with diametrically opposed portions of saidcoating when said structure is positioned between said hammers wherebysaid portions of said coating are crushed, and means for vibrating oneof said hammers in a path transverse to the longitudinal axis of saidstructure whereby an annular portion of said coating is crushed.

References Cited in the file of this patent UNITED STATES PATENTS878,493 Barnes Feb. 11, 1908 1,726,623 Hollnagel Sept. 3, 1929 1,831,115Holmes Nov. 10, 1931 1,929,921 Gaylord Oct. 10, 1933 2,037,421 LittlerApr. 14, 1936 FOREIGN PATENTS 481,662 Great Britain Mar. 16, 1938

